Specifications

AirPrime Embedded Module Hardware Integration Guide
42 Proprietary and Confidential 2130114
Interference from other wireless devices
Wireless devices operating inside the host device can cause interference that
affects the module.
To determine the most suitable locations for antennas on your host device,
evaluate each wireless device’s radio system, considering the following:
• Any harmonics, sub-harmonics, or cross-products of signals generated by
wireless devices that fall in the module’s Rx range may cause spurious
response, resulting in decreased Rx performance.
• The Tx power and corresponding broadband noise of other wireless devices
may overload or increase the noise floor of the module’s receiver, resulting in
Rx desense.
The severity of this interference depends on the closeness of the other antennas
to the module’s antenna. To determine suitable locations for each wireless
device’s antenna, thoroughly evaluate your host device’s design.
Device-generated RF
Note: The module can
cause interference with
other devices such as
hearing aids and on-board
speakers.
Wireless devices such as
AirPrime embedded
modules transmit in bursts
(pulse transients) for set
durations (RF burst
frequencies). Hearing aids
and speakers convert
these burst frequencies
into audible frequencies,
resulting in audible noise.
All electronic computing devices generate RF interference that can negatively
affect the receive sensitivity of the module.
The proximity of host electronics to the antenna in wireless devices can contribute
to decreased Rx performance. Components that are most likely to cause this
include:
• Microprocessor and memory
• Display panel and display drivers
• Switching-mode power supplies
These and other high-speed devices (in particular, the processor) can decrease
Rx performance because they run at frequencies of tens of MHz. The rapid rise
and fall of these clock signals generates higher-order harmonics that often fall
within the operating frequency band of the module, affecting the module’s receive
sensitivity.
Example
On a sub-system running at 40 MHz, the 22nd harmonic falls at 880 MHz, which
is within the cellular receive frequency band.
Note: In practice, there are usually numerous interfering frequencies and harmonics. The
net effect can be a series of desensitized receive channels.